In recent years, with the progress of the Ethernet (Registered Trademark) technology and Internet Protocol (IP) technology, IP integration of communication networks (hereinafter merely referred to as networks in some cases) has been rapidly progressed. This trend spreads to network providers. As a result, for each of carrier networks operated by communication carriers, the improvement of the efficiency of transmission has been promoted by changing a transmission technique from synchronous digital hierarchy (SDH) transmission to packet transmission in order to increase a demand for IP traffic and reduce power to be consumed and the cost of equipment and facilities.
The SDH transmission and the packet transmission are different in terms of the efficiencies of the transmission as follows. The SDH transmission is a time division multiplexing (TDM)-based technique and occupies time slots even when data to be transmitted does not exist. The packet transmission enables transmission for another communication service such as best-effort delivery when data to be transmitted does not exist. For the packet transmission, the efficiency of using lines is high.
For the carrier networks, even when the packet transmission is performed, rout management corresponding to the SDH transmission, or static path setting, is to be performed from the perspective of operational management. Specifically, the static path setting is to set a logical path (connection-oriented path) in which a connection is established in an IP network. In order to satisfy this request, a packet-based transport technique, which is called multi-protocol label switching-transport profile (MPLS-TP), has been developed.
Japanese Laid-open Patent Publication No. 2001-345810 and No. 10-190654 are examples of related art.